[codex] Structure mobile project thread validation errors

[juliusmarminge]

Summary

Mobile project-thread creation represented two distinct input failures as generic Error values. That discarded the environment, project, and creation-mode context needed to correlate repeated failures, and made both cases indistinguishable except for their message text.

This change introduces separate Schema error classes for a missing task and a missing worktree base branch. The task error records the environment, project, and environment mode; the branch error records the environment and project. Their messages remain stable and are derived from the error type rather than an opaque reason string. A focused validation function now returns those errors before the command is dispatched, and the existing user-facing pending error behavior is unchanged.

No behavior test was added for this pure validation refactor.

Validation

• pnpm vp check (passes with the repository existing warnings)
• pnpm vp run typecheck
• pnpm vp run lint:mobile

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Note

Low Risk
Client-side input validation only; behavior and displayed messages are unchanged aside from failure values being tagged errors instead of plain Error.

Overview
Project thread creation on mobile now validates through validateProjectThreadCreation instead of inline checks that threw generic Error values.

Two Effect Schema tagged errors cover the same cases as before: missing task text (includes environment, project, and local/worktree mode) and missing base branch for worktree creation (includes environment and project). use-project-actions still surfaces the same user-facing strings via setPendingConnectionError, but failures are returned as AsyncResult.failure(Cause.fail(validationError)) so callers can distinguish error kinds by type.

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Note

Replace generic errors with tagged validation errors for project thread creation

• Adds projectThreadCreationValidation.ts with two tagged error classes (ProjectThreadTaskRequiredError, ProjectThreadBaseBranchRequiredError) and a validateProjectThreadCreation function that returns the appropriate error or null.
• Updates useCreateProjectThread in use-project-actions.ts to use the new validation function, replacing ad-hoc Error instances with structured tagged errors.
• Failure messages shown to users are unchanged; only the error type changes from generic Error to a tagged schema type.

^{Macroscope summarized 4e208c3.}

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[macroscopeapp]

Approvability

Verdict: Approved

This is a straightforward refactor extracting validation logic into structured error classes. The only behavioral change is adding .trim() to reject whitespace-only messages, which is a sensible minor fix. Changes are self-contained and well-tested.

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